Community Forums

MojaveJoe · 04-29-2019, 07:41 PM

Well, I did the basic maintenance on my AC when I had it off the roof. Cleaned the fins and installed a new Micro-Air kit to run it on a 2K gen.

It ran and sounded great after reinstall.
Now after sitting 3 months, and 5 seconds after fan begins blowing, a loud deep drone sound develops immediately. It is so loud and obnoxious I couldn't stay in the trailer more than 10 seconds, before turning it off.

Wondering what the deep sound may be coming from?

Any and all advice and experiences welcome.
Thanks.

FL420 · 04-29-2019, 07:44 PM

One of these?[emoji41]
https://en.m.wikipedia.org/wiki/Lockheed_D-21

MojaveJoe · 04-29-2019, 07:54 PM

If one of those lit the afterburner in the neighbors driveway the sound inside the trailer would be similar if not quite as loud.

clifford j · 04-30-2019, 05:18 AM

Re-mounting using the same gaskets may be the problem, second thing is the amount of torque on the mounting screws. I'd look there first.

CLIFFORD

**Spdracr39** · 04-30-2019, 05:33 AM

Could a piece if insulation be hitting the fan? My S&B a/c sounded like a jet idling and that's all it was.

MojaveJoe · 04-30-2019, 08:26 AM

I will check for mounting bolt torque and possible insulation hitting fan. On reinstall I used a new roof gasket and compressed it about 1/2.
Thanks for your input. Will post what I find.

clifford j · 04-30-2019, 02:28 PM

Mojavejoe, sounds like you have a leg up on it, let us know what you find. Has to be something stupid happening, it was good before,now it went south. Your symptoms sound like the unit is vibrating the roof . MHO

CLIFFORD

redhooker · 04-30-2019, 07:57 PM

We had the exact same problem like Clifford mentioned when the dealer over torqued our new unit. It made the entire trailer sound like a sub woofer when the compressor kicked on. Once the torque was fixed (loosened), the sound went away. The gasket did need to be replaced as they had crushed it.

mobilemike · 05-01-2019, 09:15 AM

Could the compressor have slipped off one of its rubber mounts during maneuvers

MojaveJoe · 05-01-2019, 07:27 PM

Well, I removed the ceiling grill and loosened the hold down bolts enough so I could see light and move the AC unit around by lifting and pushing. NO drone sound change.
Went on the roof removed cowling and couldn't hear the drone sound but could hear a high speed tap,tap,tap... coming from the compressor. Looked around for anything loose. Nothing. Compressor grommets looked OK, but old. Compressor charge lines were hot adn cold as expected.
Went back inside and noted that the air coming from the A/C was ice cold and blowing strong. So I cycled the A/C off, waited a few minutes then back on. This time it took 2 minutes for the drone sound to come back, instead of 5 seconds when it is non-op overnight. Why? Because, it took 2 minutes for the compressor to come back on. No drone sound at all with only fan blowing in the beginning.

Tightened mounting bolts slightly. Sat down and pondered why only when the compressor kicks on? Fatigue? Wasn't used more than 6 months of the last 15 years?
Also noted drone sound not noticeable if you stand/sit in the exact center of the main floor, front or rear of the A/C unit. Move to the side and it is very noticeable.

Ready to take it to an RV repair shop and let them diagnose the problem.

Any and all advice welcome.

clifford j · 05-02-2019, 01:17 AM

Anytime you move a frig not in the upright position the thumb rule is to let it stay in vert position as long as it was laying down before you turn the unit on. The oil in the coolant media will settle out in other areas it's not supposed to be in. Over time it will migrate back to where it belongs. Just a thought.

CLIFFORD

mobilemike · 05-02-2019, 10:11 AM

I would climb back on the roof and start the unit and wait for the sound. Then put my hand on the compressor and see if the sound changes. The condenser coil mount may be cracked and vibrating. Put your hand on everything.

MojaveJoe · 05-02-2019, 01:58 PM

Loosened mounting bolts 1 1/2" then went on roof, lifted AC and supported on edges with round foam pipe insulation. No gasket contact with roof. Went down and turned on AC....voila' NO drone noise!
Decided to leave AC supported off roof for a week to give gasket time to expand back to original thickness and try install again with less compression. Im thinking about 50% compression should do it. Maybe less. May add an extras gasket strip to rear of unit to get roof contact before 50% compression. That's if I have to replace the 4 month old gasket. More to follow.